Aggregator

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0127 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns are expected to be limited for Wednesday across the country. The upper-level low currently over parts of the Pacific Northwest is forecast to de-amplify and drift east into the Plains. As this occurs, weak ascent will support widespread cloud cover as well as isolated to scattered showers and thunderstorms across the central Rockies to central Plains. The surface pressure trough currently in place along the High Plains will shift east/southeast through the day, and while breezy conditions are likely just ahead of the boundary, increasing moisture return into the Plains will modulate diurnal RH reductions. Across the West, building surface high pressure should limit wind speeds. Consequently, the potential for elevated fire weather concerns appears limited with no highlights required. ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0127 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns are expected to be limited for Wednesday across the country. The upper-level low currently over parts of the Pacific Northwest is forecast to de-amplify and drift east into the Plains. As this occurs, weak ascent will support widespread cloud cover as well as isolated to scattered showers and thunderstorms across the central Rockies to central Plains. The surface pressure trough currently in place along the High Plains will shift east/southeast through the day, and while breezy conditions are likely just ahead of the boundary, increasing moisture return into the Plains will modulate diurnal RH reductions. Across the West, building surface high pressure should limit wind speeds. Consequently, the potential for elevated fire weather concerns appears limited with no highlights required. ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0127 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns are expected to be limited for Wednesday across the country. The upper-level low currently over parts of the Pacific Northwest is forecast to de-amplify and drift east into the Plains. As this occurs, weak ascent will support widespread cloud cover as well as isolated to scattered showers and thunderstorms across the central Rockies to central Plains. The surface pressure trough currently in place along the High Plains will shift east/southeast through the day, and while breezy conditions are likely just ahead of the boundary, increasing moisture return into the Plains will modulate diurnal RH reductions. Across the West, building surface high pressure should limit wind speeds. Consequently, the potential for elevated fire weather concerns appears limited with no highlights required. ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0127 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns are expected to be limited for Wednesday across the country. The upper-level low currently over parts of the Pacific Northwest is forecast to de-amplify and drift east into the Plains. As this occurs, weak ascent will support widespread cloud cover as well as isolated to scattered showers and thunderstorms across the central Rockies to central Plains. The surface pressure trough currently in place along the High Plains will shift east/southeast through the day, and while breezy conditions are likely just ahead of the boundary, increasing moisture return into the Plains will modulate diurnal RH reductions. Across the West, building surface high pressure should limit wind speeds. Consequently, the potential for elevated fire weather concerns appears limited with no highlights required. ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into today across parts of the northern Great Basin/northern Rockies as well as the Plains. The upper trough currently over OR is forecast to slowly shift east over the next 24 hours, reaching the northern Rockies by early Wednesday. As this occurs, breezy surface winds within the dry slot of the maturing low will support dry/windy conditions across parts of NV and ID. Over the Plains, a tightening surface pressure gradient will maintain windy conditions through the afternoon, resulting in areas of elevated to critical fire weather conditions. ...Nevada into Idaho... A pronounced dry slot is developing in low-level water-vapor imagery across the northwestern Great Basin/southern OR as the upper low continues to mature. This dry slot is forecast to spread east through this afternoon, which will limit cloud and precipitation chances for northern NV and central to eastern ID and help support RH reductions into the teens. Numerous lightning strikes have been observed over the past 24 hours across this region with GOES IR imagery showing active large fires as of 05 UTC. This fire activity demonstrates the very receptive nature of the current fuel landscape (with the exception of the few locations that received wetting rainfall), and any holdover fires that resulted from the recent lightning activity may become more active today as west/southwest winds increase by late afternoon. Latest deterministic and ensemble solutions continue to suggest 15-20 mph winds will be common, especially through the Snake River Plain of southern/eastern ID and in the lee of the Independence and Ruby Mountains in northeast NV. A few locations may see periods of critical wind/RH conditions, but recent guidance suggests elevated conditions are more likely. Away from the dry slot, isolated to scattered thunderstorms are expected again today across the broader central/northern Rockies region. Forecast storm motions near 30 knots and PWAT values between 0.6 to 0.8 inches suggest dry lightning strikes are possible. However, higher MLCAPE values and lower LCL heights compared to yesterday (Monday) are mitigating factors for predominantly dry thunderstorms. Additionally, latest guidance shows a better QPF signal compared to previous days, which further limits confidence in the dry lightning threat. While this concern precludes risk highlights, any lightning strike may support fire starts given the very dry fuel conditions (ERCs above the 90th percentile). ...Wyoming into Nebraska and South Dakota... Surface pressure has been steadily falling across western NE/SD over the past 12-24 hours, and is expected to fall further through the afternoon as a lee trough continues to deepen. This will maintain breezy southerly winds across the central Plains as well as strengthen westerly downslope flow across eastern WY this afternoon. Downslope warming/drying will result in another day of 15-20% RH minimums across eastern WY and far western NE/SD. Elevated fire weather conditions appear likely within the downslope regime prior to the arrival of clouds (and potentially showers/thunderstorms) around early evening. To the east, modest moisture return into the Plains is ongoing, which will result in a zonal moisture gradient across the Plains by mid afternoon. Recent solutions suggest that the strongest winds may lie within this moisture gradient, resulting in a somewhat confined corridor of elevated fire weather conditions where 15-25 mph winds (gusting to 30-35 mph at times) will overlap with 15-25% RH values. Although guidance occasionally struggles to accurately capture the degree of boundary-layer mixing within these return flow regimes, latest deterministic solutions appear to be capturing moisture trends well and don't show substantial signs of a moist bias. This lends confidence to the ongoing forecast of predominantly elevated fire weather conditions across the region (although some locations may see periods of critical conditions). ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into today across parts of the northern Great Basin/northern Rockies as well as the Plains. The upper trough currently over OR is forecast to slowly shift east over the next 24 hours, reaching the northern Rockies by early Wednesday. As this occurs, breezy surface winds within the dry slot of the maturing low will support dry/windy conditions across parts of NV and ID. Over the Plains, a tightening surface pressure gradient will maintain windy conditions through the afternoon, resulting in areas of elevated to critical fire weather conditions. ...Nevada into Idaho... A pronounced dry slot is developing in low-level water-vapor imagery across the northwestern Great Basin/southern OR as the upper low continues to mature. This dry slot is forecast to spread east through this afternoon, which will limit cloud and precipitation chances for northern NV and central to eastern ID and help support RH reductions into the teens. Numerous lightning strikes have been observed over the past 24 hours across this region with GOES IR imagery showing active large fires as of 05 UTC. This fire activity demonstrates the very receptive nature of the current fuel landscape (with the exception of the few locations that received wetting rainfall), and any holdover fires that resulted from the recent lightning activity may become more active today as west/southwest winds increase by late afternoon. Latest deterministic and ensemble solutions continue to suggest 15-20 mph winds will be common, especially through the Snake River Plain of southern/eastern ID and in the lee of the Independence and Ruby Mountains in northeast NV. A few locations may see periods of critical wind/RH conditions, but recent guidance suggests elevated conditions are more likely. Away from the dry slot, isolated to scattered thunderstorms are expected again today across the broader central/northern Rockies region. Forecast storm motions near 30 knots and PWAT values between 0.6 to 0.8 inches suggest dry lightning strikes are possible. However, higher MLCAPE values and lower LCL heights compared to yesterday (Monday) are mitigating factors for predominantly dry thunderstorms. Additionally, latest guidance shows a better QPF signal compared to previous days, which further limits confidence in the dry lightning threat. While this concern precludes risk highlights, any lightning strike may support fire starts given the very dry fuel conditions (ERCs above the 90th percentile). ...Wyoming into Nebraska and South Dakota... Surface pressure has been steadily falling across western NE/SD over the past 12-24 hours, and is expected to fall further through the afternoon as a lee trough continues to deepen. This will maintain breezy southerly winds across the central Plains as well as strengthen westerly downslope flow across eastern WY this afternoon. Downslope warming/drying will result in another day of 15-20% RH minimums across eastern WY and far western NE/SD. Elevated fire weather conditions appear likely within the downslope regime prior to the arrival of clouds (and potentially showers/thunderstorms) around early evening. To the east, modest moisture return into the Plains is ongoing, which will result in a zonal moisture gradient across the Plains by mid afternoon. Recent solutions suggest that the strongest winds may lie within this moisture gradient, resulting in a somewhat confined corridor of elevated fire weather conditions where 15-25 mph winds (gusting to 30-35 mph at times) will overlap with 15-25% RH values. Although guidance occasionally struggles to accurately capture the degree of boundary-layer mixing within these return flow regimes, latest deterministic solutions appear to be capturing moisture trends well and don't show substantial signs of a moist bias. This lends confidence to the ongoing forecast of predominantly elevated fire weather conditions across the region (although some locations may see periods of critical conditions). ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into today across parts of the northern Great Basin/northern Rockies as well as the Plains. The upper trough currently over OR is forecast to slowly shift east over the next 24 hours, reaching the northern Rockies by early Wednesday. As this occurs, breezy surface winds within the dry slot of the maturing low will support dry/windy conditions across parts of NV and ID. Over the Plains, a tightening surface pressure gradient will maintain windy conditions through the afternoon, resulting in areas of elevated to critical fire weather conditions. ...Nevada into Idaho... A pronounced dry slot is developing in low-level water-vapor imagery across the northwestern Great Basin/southern OR as the upper low continues to mature. This dry slot is forecast to spread east through this afternoon, which will limit cloud and precipitation chances for northern NV and central to eastern ID and help support RH reductions into the teens. Numerous lightning strikes have been observed over the past 24 hours across this region with GOES IR imagery showing active large fires as of 05 UTC. This fire activity demonstrates the very receptive nature of the current fuel landscape (with the exception of the few locations that received wetting rainfall), and any holdover fires that resulted from the recent lightning activity may become more active today as west/southwest winds increase by late afternoon. Latest deterministic and ensemble solutions continue to suggest 15-20 mph winds will be common, especially through the Snake River Plain of southern/eastern ID and in the lee of the Independence and Ruby Mountains in northeast NV. A few locations may see periods of critical wind/RH conditions, but recent guidance suggests elevated conditions are more likely. Away from the dry slot, isolated to scattered thunderstorms are expected again today across the broader central/northern Rockies region. Forecast storm motions near 30 knots and PWAT values between 0.6 to 0.8 inches suggest dry lightning strikes are possible. However, higher MLCAPE values and lower LCL heights compared to yesterday (Monday) are mitigating factors for predominantly dry thunderstorms. Additionally, latest guidance shows a better QPF signal compared to previous days, which further limits confidence in the dry lightning threat. While this concern precludes risk highlights, any lightning strike may support fire starts given the very dry fuel conditions (ERCs above the 90th percentile). ...Wyoming into Nebraska and South Dakota... Surface pressure has been steadily falling across western NE/SD over the past 12-24 hours, and is expected to fall further through the afternoon as a lee trough continues to deepen. This will maintain breezy southerly winds across the central Plains as well as strengthen westerly downslope flow across eastern WY this afternoon. Downslope warming/drying will result in another day of 15-20% RH minimums across eastern WY and far western NE/SD. Elevated fire weather conditions appear likely within the downslope regime prior to the arrival of clouds (and potentially showers/thunderstorms) around early evening. To the east, modest moisture return into the Plains is ongoing, which will result in a zonal moisture gradient across the Plains by mid afternoon. Recent solutions suggest that the strongest winds may lie within this moisture gradient, resulting in a somewhat confined corridor of elevated fire weather conditions where 15-25 mph winds (gusting to 30-35 mph at times) will overlap with 15-25% RH values. Although guidance occasionally struggles to accurately capture the degree of boundary-layer mixing within these return flow regimes, latest deterministic solutions appear to be capturing moisture trends well and don't show substantial signs of a moist bias. This lends confidence to the ongoing forecast of predominantly elevated fire weather conditions across the region (although some locations may see periods of critical conditions). ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into today across parts of the northern Great Basin/northern Rockies as well as the Plains. The upper trough currently over OR is forecast to slowly shift east over the next 24 hours, reaching the northern Rockies by early Wednesday. As this occurs, breezy surface winds within the dry slot of the maturing low will support dry/windy conditions across parts of NV and ID. Over the Plains, a tightening surface pressure gradient will maintain windy conditions through the afternoon, resulting in areas of elevated to critical fire weather conditions. ...Nevada into Idaho... A pronounced dry slot is developing in low-level water-vapor imagery across the northwestern Great Basin/southern OR as the upper low continues to mature. This dry slot is forecast to spread east through this afternoon, which will limit cloud and precipitation chances for northern NV and central to eastern ID and help support RH reductions into the teens. Numerous lightning strikes have been observed over the past 24 hours across this region with GOES IR imagery showing active large fires as of 05 UTC. This fire activity demonstrates the very receptive nature of the current fuel landscape (with the exception of the few locations that received wetting rainfall), and any holdover fires that resulted from the recent lightning activity may become more active today as west/southwest winds increase by late afternoon. Latest deterministic and ensemble solutions continue to suggest 15-20 mph winds will be common, especially through the Snake River Plain of southern/eastern ID and in the lee of the Independence and Ruby Mountains in northeast NV. A few locations may see periods of critical wind/RH conditions, but recent guidance suggests elevated conditions are more likely. Away from the dry slot, isolated to scattered thunderstorms are expected again today across the broader central/northern Rockies region. Forecast storm motions near 30 knots and PWAT values between 0.6 to 0.8 inches suggest dry lightning strikes are possible. However, higher MLCAPE values and lower LCL heights compared to yesterday (Monday) are mitigating factors for predominantly dry thunderstorms. Additionally, latest guidance shows a better QPF signal compared to previous days, which further limits confidence in the dry lightning threat. While this concern precludes risk highlights, any lightning strike may support fire starts given the very dry fuel conditions (ERCs above the 90th percentile). ...Wyoming into Nebraska and South Dakota... Surface pressure has been steadily falling across western NE/SD over the past 12-24 hours, and is expected to fall further through the afternoon as a lee trough continues to deepen. This will maintain breezy southerly winds across the central Plains as well as strengthen westerly downslope flow across eastern WY this afternoon. Downslope warming/drying will result in another day of 15-20% RH minimums across eastern WY and far western NE/SD. Elevated fire weather conditions appear likely within the downslope regime prior to the arrival of clouds (and potentially showers/thunderstorms) around early evening. To the east, modest moisture return into the Plains is ongoing, which will result in a zonal moisture gradient across the Plains by mid afternoon. Recent solutions suggest that the strongest winds may lie within this moisture gradient, resulting in a somewhat confined corridor of elevated fire weather conditions where 15-25 mph winds (gusting to 30-35 mph at times) will overlap with 15-25% RH values. Although guidance occasionally struggles to accurately capture the degree of boundary-layer mixing within these return flow regimes, latest deterministic solutions appear to be capturing moisture trends well and don't show substantial signs of a moist bias. This lends confidence to the ongoing forecast of predominantly elevated fire weather conditions across the region (although some locations may see periods of critical conditions). ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into today across parts of the northern Great Basin/northern Rockies as well as the Plains. The upper trough currently over OR is forecast to slowly shift east over the next 24 hours, reaching the northern Rockies by early Wednesday. As this occurs, breezy surface winds within the dry slot of the maturing low will support dry/windy conditions across parts of NV and ID. Over the Plains, a tightening surface pressure gradient will maintain windy conditions through the afternoon, resulting in areas of elevated to critical fire weather conditions. ...Nevada into Idaho... A pronounced dry slot is developing in low-level water-vapor imagery across the northwestern Great Basin/southern OR as the upper low continues to mature. This dry slot is forecast to spread east through this afternoon, which will limit cloud and precipitation chances for northern NV and central to eastern ID and help support RH reductions into the teens. Numerous lightning strikes have been observed over the past 24 hours across this region with GOES IR imagery showing active large fires as of 05 UTC. This fire activity demonstrates the very receptive nature of the current fuel landscape (with the exception of the few locations that received wetting rainfall), and any holdover fires that resulted from the recent lightning activity may become more active today as west/southwest winds increase by late afternoon. Latest deterministic and ensemble solutions continue to suggest 15-20 mph winds will be common, especially through the Snake River Plain of southern/eastern ID and in the lee of the Independence and Ruby Mountains in northeast NV. A few locations may see periods of critical wind/RH conditions, but recent guidance suggests elevated conditions are more likely. Away from the dry slot, isolated to scattered thunderstorms are expected again today across the broader central/northern Rockies region. Forecast storm motions near 30 knots and PWAT values between 0.6 to 0.8 inches suggest dry lightning strikes are possible. However, higher MLCAPE values and lower LCL heights compared to yesterday (Monday) are mitigating factors for predominantly dry thunderstorms. Additionally, latest guidance shows a better QPF signal compared to previous days, which further limits confidence in the dry lightning threat. While this concern precludes risk highlights, any lightning strike may support fire starts given the very dry fuel conditions (ERCs above the 90th percentile). ...Wyoming into Nebraska and South Dakota... Surface pressure has been steadily falling across western NE/SD over the past 12-24 hours, and is expected to fall further through the afternoon as a lee trough continues to deepen. This will maintain breezy southerly winds across the central Plains as well as strengthen westerly downslope flow across eastern WY this afternoon. Downslope warming/drying will result in another day of 15-20% RH minimums across eastern WY and far western NE/SD. Elevated fire weather conditions appear likely within the downslope regime prior to the arrival of clouds (and potentially showers/thunderstorms) around early evening. To the east, modest moisture return into the Plains is ongoing, which will result in a zonal moisture gradient across the Plains by mid afternoon. Recent solutions suggest that the strongest winds may lie within this moisture gradient, resulting in a somewhat confined corridor of elevated fire weather conditions where 15-25 mph winds (gusting to 30-35 mph at times) will overlap with 15-25% RH values. Although guidance occasionally struggles to accurately capture the degree of boundary-layer mixing within these return flow regimes, latest deterministic solutions appear to be capturing moisture trends well and don't show substantial signs of a moist bias. This lends confidence to the ongoing forecast of predominantly elevated fire weather conditions across the region (although some locations may see periods of critical conditions). ..Moore.. 09/03/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/NORTHERN ROCKIES AND PLAINS INTO MUCH OF MINNESOTA... ...SUMMARY... Isolated strong to severe storms are possible on Wednesday across parts of the central and northern Rockies and Plains into parts of Minnesota. ...Synopsis... A shortwave trough initially over the Great Basin/Intermountain West is forecast to move east-southeastward and gradually deamplify on Wednesday, as it begins to merge with a more prominent upper-level trough that will cover parts of the Canadian Prairies into the northern/central Plains. Multiple embedded shortwaves within the larger trough will likely move across parts of the Dakotas and Minnesota. A weak surface wave may develop during the afternoon along a cold front that will extend from parts of MN and the Dakotas into the central Plains. ...Parts of the northern/central Rockies/Plains into Minnesota... A large area of at least low-end severe potential may evolve from parts of the central/northern Rockies/Plains into Minnesota. The Marginal Risk has been maintained with some minor adjustments; further refinement to the risk area is likely if areas of relatively lower or higher threat become evident with time. Scattered thunderstorms may develop relatively early in the day across the higher terrain of CO/WY/MT, in association with the shortwave trough emerging from the Intermountain West. While low-level moisture will likely remain rather limited, steep midlevel lapse rates and modestly favorable deep-layer shear could support a few organized multicells and perhaps a marginal supercell or two, as convection spreads towards the central/northern High Plains. Isolated strong to severe gusts and hail will be possible. Some outflow consolidation could support one or more loosely organized clusters evolving with time, with a threat of strong to locally severe gusts as storms move eastward into the evening. Farther northeast, details regarding destabilization and storm development/evolution from the eastern Dakotas into MN remain uncertain. Some guidance suggests potential for an embedded shortwave or MCV to move across the region during the afternoon/evening, which could aid in isolated storm development near the front, if sufficient moistening and destabilization can occur. There will also be some potential for storms to develop and/or spread into the region from the west during the evening, as the larger-scale upper trough begins to amplify. Relatively steep midlevel lapse rates and adequate deep-layer shear could support isolated hail and damaging gusts with the strongest storms. ..Dean.. 09/03/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/NORTHERN ROCKIES AND PLAINS INTO MUCH OF MINNESOTA... ...SUMMARY... Isolated strong to severe storms are possible on Wednesday across parts of the central and northern Rockies and Plains into parts of Minnesota. ...Synopsis... A shortwave trough initially over the Great Basin/Intermountain West is forecast to move east-southeastward and gradually deamplify on Wednesday, as it begins to merge with a more prominent upper-level trough that will cover parts of the Canadian Prairies into the northern/central Plains. Multiple embedded shortwaves within the larger trough will likely move across parts of the Dakotas and Minnesota. A weak surface wave may develop during the afternoon along a cold front that will extend from parts of MN and the Dakotas into the central Plains. ...Parts of the northern/central Rockies/Plains into Minnesota... A large area of at least low-end severe potential may evolve from parts of the central/northern Rockies/Plains into Minnesota. The Marginal Risk has been maintained with some minor adjustments; further refinement to the risk area is likely if areas of relatively lower or higher threat become evident with time. Scattered thunderstorms may develop relatively early in the day across the higher terrain of CO/WY/MT, in association with the shortwave trough emerging from the Intermountain West. While low-level moisture will likely remain rather limited, steep midlevel lapse rates and modestly favorable deep-layer shear could support a few organized multicells and perhaps a marginal supercell or two, as convection spreads towards the central/northern High Plains. Isolated strong to severe gusts and hail will be possible. Some outflow consolidation could support one or more loosely organized clusters evolving with time, with a threat of strong to locally severe gusts as storms move eastward into the evening. Farther northeast, details regarding destabilization and storm development/evolution from the eastern Dakotas into MN remain uncertain. Some guidance suggests potential for an embedded shortwave or MCV to move across the region during the afternoon/evening, which could aid in isolated storm development near the front, if sufficient moistening and destabilization can occur. There will also be some potential for storms to develop and/or spread into the region from the west during the evening, as the larger-scale upper trough begins to amplify. Relatively steep midlevel lapse rates and adequate deep-layer shear could support isolated hail and damaging gusts with the strongest storms. ..Dean.. 09/03/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/NORTHERN ROCKIES AND PLAINS INTO MUCH OF MINNESOTA... ...SUMMARY... Isolated strong to severe storms are possible on Wednesday across parts of the central and northern Rockies and Plains into parts of Minnesota. ...Synopsis... A shortwave trough initially over the Great Basin/Intermountain West is forecast to move east-southeastward and gradually deamplify on Wednesday, as it begins to merge with a more prominent upper-level trough that will cover parts of the Canadian Prairies into the northern/central Plains. Multiple embedded shortwaves within the larger trough will likely move across parts of the Dakotas and Minnesota. A weak surface wave may develop during the afternoon along a cold front that will extend from parts of MN and the Dakotas into the central Plains. ...Parts of the northern/central Rockies/Plains into Minnesota... A large area of at least low-end severe potential may evolve from parts of the central/northern Rockies/Plains into Minnesota. The Marginal Risk has been maintained with some minor adjustments; further refinement to the risk area is likely if areas of relatively lower or higher threat become evident with time. Scattered thunderstorms may develop relatively early in the day across the higher terrain of CO/WY/MT, in association with the shortwave trough emerging from the Intermountain West. While low-level moisture will likely remain rather limited, steep midlevel lapse rates and modestly favorable deep-layer shear could support a few organized multicells and perhaps a marginal supercell or two, as convection spreads towards the central/northern High Plains. Isolated strong to severe gusts and hail will be possible. Some outflow consolidation could support one or more loosely organized clusters evolving with time, with a threat of strong to locally severe gusts as storms move eastward into the evening. Farther northeast, details regarding destabilization and storm development/evolution from the eastern Dakotas into MN remain uncertain. Some guidance suggests potential for an embedded shortwave or MCV to move across the region during the afternoon/evening, which could aid in isolated storm development near the front, if sufficient moistening and destabilization can occur. There will also be some potential for storms to develop and/or spread into the region from the west during the evening, as the larger-scale upper trough begins to amplify. Relatively steep midlevel lapse rates and adequate deep-layer shear could support isolated hail and damaging gusts with the strongest storms. ..Dean.. 09/03/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/NORTHERN ROCKIES AND PLAINS INTO MUCH OF MINNESOTA... ...SUMMARY... Isolated strong to severe storms are possible on Wednesday across parts of the central and northern Rockies and Plains into parts of Minnesota. ...Synopsis... A shortwave trough initially over the Great Basin/Intermountain West is forecast to move east-southeastward and gradually deamplify on Wednesday, as it begins to merge with a more prominent upper-level trough that will cover parts of the Canadian Prairies into the northern/central Plains. Multiple embedded shortwaves within the larger trough will likely move across parts of the Dakotas and Minnesota. A weak surface wave may develop during the afternoon along a cold front that will extend from parts of MN and the Dakotas into the central Plains. ...Parts of the northern/central Rockies/Plains into Minnesota... A large area of at least low-end severe potential may evolve from parts of the central/northern Rockies/Plains into Minnesota. The Marginal Risk has been maintained with some minor adjustments; further refinement to the risk area is likely if areas of relatively lower or higher threat become evident with time. Scattered thunderstorms may develop relatively early in the day across the higher terrain of CO/WY/MT, in association with the shortwave trough emerging from the Intermountain West. While low-level moisture will likely remain rather limited, steep midlevel lapse rates and modestly favorable deep-layer shear could support a few organized multicells and perhaps a marginal supercell or two, as convection spreads towards the central/northern High Plains. Isolated strong to severe gusts and hail will be possible. Some outflow consolidation could support one or more loosely organized clusters evolving with time, with a threat of strong to locally severe gusts as storms move eastward into the evening. Farther northeast, details regarding destabilization and storm development/evolution from the eastern Dakotas into MN remain uncertain. Some guidance suggests potential for an embedded shortwave or MCV to move across the region during the afternoon/evening, which could aid in isolated storm development near the front, if sufficient moistening and destabilization can occur. There will also be some potential for storms to develop and/or spread into the region from the west during the evening, as the larger-scale upper trough begins to amplify. Relatively steep midlevel lapse rates and adequate deep-layer shear could support isolated hail and damaging gusts with the strongest storms. ..Dean.. 09/03/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Tue Sep 03 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/NORTHERN ROCKIES AND PLAINS INTO MUCH OF MINNESOTA... ...SUMMARY... Isolated strong to severe storms are possible on Wednesday across parts of the central and northern Rockies and Plains into parts of Minnesota. ...Synopsis... A shortwave trough initially over the Great Basin/Intermountain West is forecast to move east-southeastward and gradually deamplify on Wednesday, as it begins to merge with a more prominent upper-level trough that will cover parts of the Canadian Prairies into the northern/central Plains. Multiple embedded shortwaves within the larger trough will likely move across parts of the Dakotas and Minnesota. A weak surface wave may develop during the afternoon along a cold front that will extend from parts of MN and the Dakotas into the central Plains. ...Parts of the northern/central Rockies/Plains into Minnesota... A large area of at least low-end severe potential may evolve from parts of the central/northern Rockies/Plains into Minnesota. The Marginal Risk has been maintained with some minor adjustments; further refinement to the risk area is likely if areas of relatively lower or higher threat become evident with time. Scattered thunderstorms may develop relatively early in the day across the higher terrain of CO/WY/MT, in association with the shortwave trough emerging from the Intermountain West. While low-level moisture will likely remain rather limited, steep midlevel lapse rates and modestly favorable deep-layer shear could support a few organized multicells and perhaps a marginal supercell or two, as convection spreads towards the central/northern High Plains. Isolated strong to severe gusts and hail will be possible. Some outflow consolidation could support one or more loosely organized clusters evolving with time, with a threat of strong to locally severe gusts as storms move eastward into the evening. Farther northeast, details regarding destabilization and storm development/evolution from the eastern Dakotas into MN remain uncertain. Some guidance suggests potential for an embedded shortwave or MCV to move across the region during the afternoon/evening, which could aid in isolated storm development near the front, if sufficient moistening and destabilization can occur. There will also be some potential for storms to develop and/or spread into the region from the west during the evening, as the larger-scale upper trough begins to amplify. Relatively steep midlevel lapse rates and adequate deep-layer shear could support isolated hail and damaging gusts with the strongest storms. ..Dean.. 09/03/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING ACROSS PARTS OF CENTRAL IDAHO...MUCH OF SOUTHERN MONTANA...WYOMING...MUCH OF NORTHERN UTAH AND ADJACENT NORTHWESTERN COLORADO...INTO PARTS OF THE WESTERN DAKOTAS... ...SUMMARY... Thunderstorms developing across the northern Rockies and adjacent portions of the Great Basin by this afternoon may produce scattered strong to locally severe wind gusts, before spreading eastward toward the northern Great Plains into this evening. ...Synopsis... Downstream of split mid/upper flow across the eastern Pacific, Alaska and Canadian Yukon vicinity, the stronger westerlies remain confined to the higher latitudes, with weaker zonal flow prevailing across the northern tier of the U.S., on the northern periphery of weak/suppressed subtropical ridging. Seasonably moist boundary-layer air has generally become confined to the southern tier of the U.S., to the south of notable surface ridging. Little change appears likely through this period, though the center of the ridge may shift from the lower Great Lakes/upper Ohio Valley into the northern Mid Atlantic. It does appear that the westerlies may undergo some amplification across the northeastern Pacific into Canada later today through tonight, including building mid-level ridging offshore of the Pacific Northwest and British Columbia coast and digging mid-level troughing to the lee of the Canadian Rockies. As this occurs, a remnant mid-level trough over the interior northwestern U.S. is forecast to slowly shift into and across the northern Rockies. ...Northern Intermountain Region and Rockies... Models indicate that the mid-level trough will weaken while shifting eastward today, but it still appears that mid-level forcing for ascent and cooling will remain sufficient to support continuing convective development, including considerable thunderstorm activity this afternoon and evening across the higher terrain. Near the mid-level cold core, destabilization, including mixed-layer CAPE on the order of 500-1000 J/kg, might support a few thunderstorms capable of producing marginally severe hail across the mountains of southwestern Montana. Otherwise, more modest CAPE, based above a warm and deeply mixed boundary layer, may still become supportive of locally strong to severe downburst winds across the higher terrain of western Wyoming and northern Utah, into the Great Salt Lake Desert. Eastward into the northern high plains, severe weather potential, and the extent to which destabilization is able to maintain thunderstorm development, remains more uncertain. However, some model output, perhaps most notably the past few runs of the NAM, has been suggestive that convective development near/north of the Absaroka Range and Big Horn Basin vicinity may generate sufficient consolidating outflow to support a substantive east-southeastward propagating surface cold pool to the lee of the higher terrain. Although 03/00Z NAM forecast soundings, for example, are not particularly indicative that vigorous thunderstorm development will be maintained, they suggest that 35-50 kt winds may accompany a surging gust front, in this run across southeastern Montana and adjacent northeastern Wyoming by late evening and into western South Dakota overnight. ..Kerr/Moore.. 09/03/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING ACROSS PARTS OF CENTRAL IDAHO...MUCH OF SOUTHERN MONTANA...WYOMING...MUCH OF NORTHERN UTAH AND ADJACENT NORTHWESTERN COLORADO...INTO PARTS OF THE WESTERN DAKOTAS... ...SUMMARY... Thunderstorms developing across the northern Rockies and adjacent portions of the Great Basin by this afternoon may produce scattered strong to locally severe wind gusts, before spreading eastward toward the northern Great Plains into this evening. ...Synopsis... Downstream of split mid/upper flow across the eastern Pacific, Alaska and Canadian Yukon vicinity, the stronger westerlies remain confined to the higher latitudes, with weaker zonal flow prevailing across the northern tier of the U.S., on the northern periphery of weak/suppressed subtropical ridging. Seasonably moist boundary-layer air has generally become confined to the southern tier of the U.S., to the south of notable surface ridging. Little change appears likely through this period, though the center of the ridge may shift from the lower Great Lakes/upper Ohio Valley into the northern Mid Atlantic. It does appear that the westerlies may undergo some amplification across the northeastern Pacific into Canada later today through tonight, including building mid-level ridging offshore of the Pacific Northwest and British Columbia coast and digging mid-level troughing to the lee of the Canadian Rockies. As this occurs, a remnant mid-level trough over the interior northwestern U.S. is forecast to slowly shift into and across the northern Rockies. ...Northern Intermountain Region and Rockies... Models indicate that the mid-level trough will weaken while shifting eastward today, but it still appears that mid-level forcing for ascent and cooling will remain sufficient to support continuing convective development, including considerable thunderstorm activity this afternoon and evening across the higher terrain. Near the mid-level cold core, destabilization, including mixed-layer CAPE on the order of 500-1000 J/kg, might support a few thunderstorms capable of producing marginally severe hail across the mountains of southwestern Montana. Otherwise, more modest CAPE, based above a warm and deeply mixed boundary layer, may still become supportive of locally strong to severe downburst winds across the higher terrain of western Wyoming and northern Utah, into the Great Salt Lake Desert. Eastward into the northern high plains, severe weather potential, and the extent to which destabilization is able to maintain thunderstorm development, remains more uncertain. However, some model output, perhaps most notably the past few runs of the NAM, has been suggestive that convective development near/north of the Absaroka Range and Big Horn Basin vicinity may generate sufficient consolidating outflow to support a substantive east-southeastward propagating surface cold pool to the lee of the higher terrain. Although 03/00Z NAM forecast soundings, for example, are not particularly indicative that vigorous thunderstorm development will be maintained, they suggest that 35-50 kt winds may accompany a surging gust front, in this run across southeastern Montana and adjacent northeastern Wyoming by late evening and into western South Dakota overnight. ..Kerr/Moore.. 09/03/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING ACROSS PARTS OF CENTRAL IDAHO...MUCH OF SOUTHERN MONTANA...WYOMING...MUCH OF NORTHERN UTAH AND ADJACENT NORTHWESTERN COLORADO...INTO PARTS OF THE WESTERN DAKOTAS... ...SUMMARY... Thunderstorms developing across the northern Rockies and adjacent portions of the Great Basin by this afternoon may produce scattered strong to locally severe wind gusts, before spreading eastward toward the northern Great Plains into this evening. ...Synopsis... Downstream of split mid/upper flow across the eastern Pacific, Alaska and Canadian Yukon vicinity, the stronger westerlies remain confined to the higher latitudes, with weaker zonal flow prevailing across the northern tier of the U.S., on the northern periphery of weak/suppressed subtropical ridging. Seasonably moist boundary-layer air has generally become confined to the southern tier of the U.S., to the south of notable surface ridging. Little change appears likely through this period, though the center of the ridge may shift from the lower Great Lakes/upper Ohio Valley into the northern Mid Atlantic. It does appear that the westerlies may undergo some amplification across the northeastern Pacific into Canada later today through tonight, including building mid-level ridging offshore of the Pacific Northwest and British Columbia coast and digging mid-level troughing to the lee of the Canadian Rockies. As this occurs, a remnant mid-level trough over the interior northwestern U.S. is forecast to slowly shift into and across the northern Rockies. ...Northern Intermountain Region and Rockies... Models indicate that the mid-level trough will weaken while shifting eastward today, but it still appears that mid-level forcing for ascent and cooling will remain sufficient to support continuing convective development, including considerable thunderstorm activity this afternoon and evening across the higher terrain. Near the mid-level cold core, destabilization, including mixed-layer CAPE on the order of 500-1000 J/kg, might support a few thunderstorms capable of producing marginally severe hail across the mountains of southwestern Montana. Otherwise, more modest CAPE, based above a warm and deeply mixed boundary layer, may still become supportive of locally strong to severe downburst winds across the higher terrain of western Wyoming and northern Utah, into the Great Salt Lake Desert. Eastward into the northern high plains, severe weather potential, and the extent to which destabilization is able to maintain thunderstorm development, remains more uncertain. However, some model output, perhaps most notably the past few runs of the NAM, has been suggestive that convective development near/north of the Absaroka Range and Big Horn Basin vicinity may generate sufficient consolidating outflow to support a substantive east-southeastward propagating surface cold pool to the lee of the higher terrain. Although 03/00Z NAM forecast soundings, for example, are not particularly indicative that vigorous thunderstorm development will be maintained, they suggest that 35-50 kt winds may accompany a surging gust front, in this run across southeastern Montana and adjacent northeastern Wyoming by late evening and into western South Dakota overnight. ..Kerr/Moore.. 09/03/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING ACROSS PARTS OF CENTRAL IDAHO...MUCH OF SOUTHERN MONTANA...WYOMING...MUCH OF NORTHERN UTAH AND ADJACENT NORTHWESTERN COLORADO...INTO PARTS OF THE WESTERN DAKOTAS... ...SUMMARY... Thunderstorms developing across the northern Rockies and adjacent portions of the Great Basin by this afternoon may produce scattered strong to locally severe wind gusts, before spreading eastward toward the northern Great Plains into this evening. ...Synopsis... Downstream of split mid/upper flow across the eastern Pacific, Alaska and Canadian Yukon vicinity, the stronger westerlies remain confined to the higher latitudes, with weaker zonal flow prevailing across the northern tier of the U.S., on the northern periphery of weak/suppressed subtropical ridging. Seasonably moist boundary-layer air has generally become confined to the southern tier of the U.S., to the south of notable surface ridging. Little change appears likely through this period, though the center of the ridge may shift from the lower Great Lakes/upper Ohio Valley into the northern Mid Atlantic. It does appear that the westerlies may undergo some amplification across the northeastern Pacific into Canada later today through tonight, including building mid-level ridging offshore of the Pacific Northwest and British Columbia coast and digging mid-level troughing to the lee of the Canadian Rockies. As this occurs, a remnant mid-level trough over the interior northwestern U.S. is forecast to slowly shift into and across the northern Rockies. ...Northern Intermountain Region and Rockies... Models indicate that the mid-level trough will weaken while shifting eastward today, but it still appears that mid-level forcing for ascent and cooling will remain sufficient to support continuing convective development, including considerable thunderstorm activity this afternoon and evening across the higher terrain. Near the mid-level cold core, destabilization, including mixed-layer CAPE on the order of 500-1000 J/kg, might support a few thunderstorms capable of producing marginally severe hail across the mountains of southwestern Montana. Otherwise, more modest CAPE, based above a warm and deeply mixed boundary layer, may still become supportive of locally strong to severe downburst winds across the higher terrain of western Wyoming and northern Utah, into the Great Salt Lake Desert. Eastward into the northern high plains, severe weather potential, and the extent to which destabilization is able to maintain thunderstorm development, remains more uncertain. However, some model output, perhaps most notably the past few runs of the NAM, has been suggestive that convective development near/north of the Absaroka Range and Big Horn Basin vicinity may generate sufficient consolidating outflow to support a substantive east-southeastward propagating surface cold pool to the lee of the higher terrain. Although 03/00Z NAM forecast soundings, for example, are not particularly indicative that vigorous thunderstorm development will be maintained, they suggest that 35-50 kt winds may accompany a surging gust front, in this run across southeastern Montana and adjacent northeastern Wyoming by late evening and into western South Dakota overnight. ..Kerr/Moore.. 09/03/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Tue Sep 03 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING ACROSS PARTS OF CENTRAL IDAHO...MUCH OF SOUTHERN MONTANA...WYOMING...MUCH OF NORTHERN UTAH AND ADJACENT NORTHWESTERN COLORADO...INTO PARTS OF THE WESTERN DAKOTAS... ...SUMMARY... Thunderstorms developing across the northern Rockies and adjacent portions of the Great Basin by this afternoon may produce scattered strong to locally severe wind gusts, before spreading eastward toward the northern Great Plains into this evening. ...Synopsis... Downstream of split mid/upper flow across the eastern Pacific, Alaska and Canadian Yukon vicinity, the stronger westerlies remain confined to the higher latitudes, with weaker zonal flow prevailing across the northern tier of the U.S., on the northern periphery of weak/suppressed subtropical ridging. Seasonably moist boundary-layer air has generally become confined to the southern tier of the U.S., to the south of notable surface ridging. Little change appears likely through this period, though the center of the ridge may shift from the lower Great Lakes/upper Ohio Valley into the northern Mid Atlantic. It does appear that the westerlies may undergo some amplification across the northeastern Pacific into Canada later today through tonight, including building mid-level ridging offshore of the Pacific Northwest and British Columbia coast and digging mid-level troughing to the lee of the Canadian Rockies. As this occurs, a remnant mid-level trough over the interior northwestern U.S. is forecast to slowly shift into and across the northern Rockies. ...Northern Intermountain Region and Rockies... Models indicate that the mid-level trough will weaken while shifting eastward today, but it still appears that mid-level forcing for ascent and cooling will remain sufficient to support continuing convective development, including considerable thunderstorm activity this afternoon and evening across the higher terrain. Near the mid-level cold core, destabilization, including mixed-layer CAPE on the order of 500-1000 J/kg, might support a few thunderstorms capable of producing marginally severe hail across the mountains of southwestern Montana. Otherwise, more modest CAPE, based above a warm and deeply mixed boundary layer, may still become supportive of locally strong to severe downburst winds across the higher terrain of western Wyoming and northern Utah, into the Great Salt Lake Desert. Eastward into the northern high plains, severe weather potential, and the extent to which destabilization is able to maintain thunderstorm development, remains more uncertain. However, some model output, perhaps most notably the past few runs of the NAM, has been suggestive that convective development near/north of the Absaroka Range and Big Horn Basin vicinity may generate sufficient consolidating outflow to support a substantive east-southeastward propagating surface cold pool to the lee of the higher terrain. Although 03/00Z NAM forecast soundings, for example, are not particularly indicative that vigorous thunderstorm development will be maintained, they suggest that 35-50 kt winds may accompany a surging gust front, in this run across southeastern Montana and adjacent northeastern Wyoming by late evening and into western South Dakota overnight. ..Kerr/Moore.. 09/03/2024 Read more

000
ABPZ20 KNHC 030523
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Mon Sep 2 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster Roberts